In an energy management system that manages the energy consumption of a plurality of sites including factories and buildings, in order to be able to generate an operation schedule for each of sites, a technique described in PTL 1 is known.
PTL 1 describes that “in order to optimize a first evaluation value and optimize a second evaluation value satisfying the optimization of the first evaluation value, in generating an operation schedule for performing a control of integrated demand power of a plurality of facilities, it is possible to optimize both the first evaluation value and the second evaluation value easily and quickly compared with a case where the optimization is collectively performed on the first evaluation value and the second evaluation value”.